Mac Screen of Death

Last night I got my second Mac Screen of Death (Panic Report) in nearly 3 years and I really don't understand why because I just had my laptop open and was doing anything and most of the applications that I usually work with were not running.

I would like to try and understand where the problem lies, and would appreciate it if someone could help me, or direct me to more info on the subject.

I did follow apple's directions to mitigating panic reports and hope that I won't see the problem again but I hate not knowing what caused it.

This is the Panic report that was sent to Apple.
I will appreciate any help in the matter, thank you!

------------
Interval Since Last Panic Report: 2419334 sec
Panics Since Last Report: 1

Sat Oct 16 15:13:40 2010
panic(cpu 0 caller 0x2269f0): "thread_invoke: preemption_level -1, possible cause: unlocking an unlocked mutex or spinlock"@/SourceCache/xnu/xnu-1504.7.4/osfmk/kern/sched_prim.c:1476
Backtrace (CPU 0), Frame : Return Address (4 potential args on stack)
0x34d6bd38 : 0x21b455 (0x5cf328 0x34d6bd6c 0x2238b1 0x0)
0x34d6bd88 : 0x2269f0 (0x58712c 0xffffffff 0x5870c4 0x2262b4)
0x34d6be08 : 0x2270f6 (0x5c1db98 0x5c1db98 0x34d6be68 0x232823)
0x34d6be78 : 0x227184 (0x0 0x0 0x0 0x3)
0x34d6be98 : 0x221948 (0x0 0x0 0x0 0x319f2d)
0x34d6beb8 : 0x4867fc (0x43e5630 0x0 0x5d36194 0x0)
0x34d6bf28 : 0x486eef (0x0 0x0 0x0 0x43e5630)
0x34d6bf68 : 0x31a281 (0x5d36194 0x43e5630 0x0 0x5d361ac)
0x34d6bfc8 : 0x29e6cc (0x5d36184 0x0 0x10 0x3df8ac4)

BSD process name corresponding to current thread: kernel_task

Mac OS version:
10F569

Kernel version:
Darwin Kernel Version 10.4.0: Fri Apr 23 18:28:53 PDT 2010; root:xnu-1504.7.4~1/RELEASE_I386
System model name: MacBook4,1 (Mac-F22788A9)

System uptime in nanoseconds: 105209549504254
unloaded kexts:
com.apple.driver.IOBluetoothHIDDriver 2.3.3f8 (addr 0x35147000, size 0x53248) - last unloaded 28965347482601
loaded kexts:
org.virtualbox.kext.VBoxNetAdp 3.2.8
org.virtualbox.kext.VBoxNetFlt 3.2.8
org.virtualbox.kext.VBoxUSB 3.2.8
org.virtualbox.kext.VBoxDrv 3.2.8
com.cisco.nke.ipsec 2.0.1
com.apple.filesystems.afpfs 9.7
com.apple.nke.asp_tcp 5.0
com.apple.filesystems.smbfs 1.6.2
com.apple.driver.AudioAUUC 1.4
com.apple.Dont Steal_Mac_OSX 7.0.0
com.apple.iokit.CHUDUtils 364
com.apple.iokit.CHUDProf 364
com.apple.driver.AppleHWSensor 1.9.3d0
com.apple.driver.AppleIntelPenrynProfile 17.1
com.apple.driver.AppleUpstreamUserClient 3.3.2
com.apple.driver.AppleIntelGMAX3100 6.1.8
com.apple.driver.AppleHDA 1.8.7f1
com.apple.driver.AudioIPCDriver 1.1.2
com.apple.driver.AppleIntelGMAX3100FB 6.1.8
com.apple.driver.SMCMotionSensor 3.0.0d4
com.apple.iokit.AppleYukon2 3.1.14b1
com.apple.driver.AirPortBrcm43xx 423.91.27
com.apple.driver.ACPI SMCPlatformPlugin 4.1.2b1
com.apple.driver.AppleLPC 1.4.12
com.apple.driver.AppleBacklight 170.0.24
com.apple.filesystems.autofs 2.1.0
com.apple.driver.AppleUSBTrackpad 1.8.1b1
com.apple.driver.AppleUSBTCKeyEventDriver 1.8.1b1
com.apple.driver.AppleUSBTCKeyboard 1.8.1b1
com.apple.driver.AppleIRController 303.8
com.apple.iokit.SCSITaskUserClient 2.6.5
com.apple.iokit.IOAHCIBlockStorage 1.6.2
com.apple.driver.AppleUSBHub 4.0.0
com.apple.driver.AppleAHCIPort 2.1.2
com.apple.driver.AppleIntelPIIXATA 2.5.1
com.apple.driver.AppleUSBEHCI 4.0.2
com.apple.driver.AppleUSBUHCI 4.0.2
com.apple.BootCache 31
com.apple.AppleFSCompression.AppleFSCompressionTypeZlib 1.0.0d1
com.apple.driver.AppleFWOHCI 4.7.1
com.apple.driver.AppleEFINVRAM 1.3.0
com.apple.driver.AppleRTC 1.3.1
com.apple.driver.AppleHPET 1.5
com.apple.driver.AppleSmartBatteryManager 160.0.0
com.apple.driver.AppleACPIButtons 1.3.2
com.apple.driver.AppleSMBIOS 1.6
com.apple.driver.AppleACPIEC 1.3.2
com.apple.driver.AppleAPIC 1.4
com.apple.driver.AppleIntelCPUPowerManagementClient 105.10.0
com.apple.security.sandbox 0
com.apple.security.quarantine 0
com.apple.nke.applicationfirewall 2.1.11
com.apple.driver.AppleIntelCPUPowerManagement 105.10.0
com.apple.driver.AppleBluetoothHIDMouse 1.4.0d7 - last loaded 47096711977927
com.apple.driver.IOBluetoothHIDDriver 2.3.3f8
com.apple.driver.AppleHIDMouse 1.4.0d7
com.apple.driver.AppleProfileReadCounterAction 17
com.apple.driver.AppleProfileTimestampAction 10
com.apple.driver.AppleProfileThreadInfoAction 14
com.apple.driver.AppleProfileRegisterStateAction 10
com.apple.driver.AppleProfileKEventAction 10
com.apple.driver.AppleProfileCallstackAction 20
com.apple.iokit.IOSurface 74.0
com.apple.iokit.IOBluetoothSerialManager 2.3.3f8
com.apple.iokit.IOSerialFamily 10.0.3
com.apple.iokit.CHUDKernLib 364
com.apple.driver.DspFuncLib 1.8.7f1
com.apple.iokit.IOAudioFamily 1.7.6fc2
com.apple.kext.OSvKernDSPLib 1.3
com.apple.iokit.IO80211Family 311.1
com.apple.iokit.AppleProfileFamily 41.4
com.apple.driver.AppleHDAController 1.8.7f1
com.apple.iokit.IOHDAFamily 1.8.7f1
com.apple.driver.AppleSMC 3.0.1d2
com.apple.driver.IOPlatformPluginFamily 4.1.2b1
com.apple.iokit.IONDRVSupport 2.1
com.apple.iokit.IOGraphicsFamily 2.1
com.apple.iokit.IOFireWireIP 2.0.3
com.apple.iokit.IONetworkingFamily 1.9
com.apple.driver.CSRUSBBluetoothHCIController 2.3.3f8
com.apple.driver.AppleUSBBluetoothHCIController 2.3.3f8
com.apple.iokit.IOBluetoothFamily 2.3.3f8
com.apple.iokit.IOUSBHIDDriver 4.0.2
com.apple.driver.AppleUSBMergeNub 4.0.0
com.apple.driver.AppleUSBComposite 3.9.0
com.apple.iokit.IOSCSIMultimediaCommandsDevice 2.6.5
com.apple.iokit.IOBDStorageFamily 1.6
com.apple.iokit.IODVDStorageFamily 1.6
com.apple.iokit.IOCDStorageFamily 1.6
com.apple.driver.XsanFilter 402.1
com.apple.iokit.IOATAPIProtocolTransport 2.5.1
com.apple.iokit.IOSCSIArchitectureModelFamily 2.6.5
com.apple.iokit.IOUSBUserClient 4.0.0
com.apple.iokit.IOAHCIFamily 2.0.4
com.apple.iokit.IOATAFamily 2.5.1
com.apple.iokit.IOUSBFamily 4.0.2
com.apple.iokit.IOFireWireFamily 4.2.6
com.apple.driver.AppleEFIRuntime 1.3.0
com.apple.iokit.IOHIDFamily 1.6.4
com.apple.iokit.IOSMBusFamily 1.1
com.apple.security.TMSafetyNet 6
com.apple.kext.AppleMatch 1.0.0d1
com.apple.driver.DiskImages 283
com.apple.iokit.IOStorageFamily 1.6.1
com.apple.driver.AppleACPIPlatform 1.3.2
com.apple.iokit.IOPCIFamily 2.6
com.apple.iokit.IOACPIFamily 1.3.0
System Profile:
Model: MacBook4,1, BootROM MB41.00C1.B00, 2 processors, Intel Core 2 Duo, 2.4 GHz, 2 GB, SMC 1.31f1
Graphics: Intel GMA X3100, GMA X3100, Built-In, 144 MB
Memory Module: global_name
AirPort: spairport wireless_card_type_airportextreme (0x14E4, 0x88), Broadcom BCM43xx 1.0 (5.10.91.27)
Bluetooth: Version 2.3.3f8, 2 service, 19 devices, 1 incoming serial ports
Network Service: Ethernet, Ethernet, en0
Serial ATA Device: Hitachi HTS542525K9SA00, 232.89 GB
Parallel ATA Device: HL-DT-ST DVDRW GSA-S10N
USB Device: Built-in iSight, 0x05ac (Apple Inc.), 0x8501, 0xfd400000
USB Device: Apple Internal Keyboard / Trackpad, 0x05ac (Apple Inc.), 0x022a, 0x5d200000
USB Device: IR Receiver, 0x05ac (Apple Inc.), 0x8242, 0x5d100000
USB Device: Bluetooth USB Host Controller, 0x05ac (Apple Inc.), 0x8205, 0x1a100000